The Wisconsin National Primate Research Center (WNPRC) base operating grant supports services and resources for research addressing human health issues utilizing non-human primate (NHP) models. Located on the campus of the University of Wisconsin-Madison, the WNPRC is fully integrated into the mission of UW-Madison, including research and training links in the several schools and colleges, basic science and clinical departments, and interdisciplinary centers and institutes. In addition, WNPRC investigators have strong research collaborations with scientists across the U.S. and internationally. The WNPRC provides a rich and integrated portfolio of cutting-edge services, resources, and scientific expertise that support NHP research with high impact and direct relevance to human and animal health and disease. This P51 Revision application requests support for maintenance and development of common marmosets (Callithrix jacchus) recently acquired from the New England Primate Research Center (NEPRC). Our specific aims to support these animals are as follows: Aim 1. To provide excellent animal holding facilities and primary enclosures for the marmosets transferred from the NEPRC. Aim 2. To implement exceptional, USDA/PHS/OLAW/AAALAC compliant husbandry and veterinary medical practices for the marmosets transferred from the NEPRC. Aim 3. To implement appropriate genetic and reproductive management for the transferred marmosets. Aim 4. To implement a prudent financial plan to support the transferred marmosets as ORIP support for the animals is progressively reduced In accomplishing the foregoing Specific Aims, we will then be poised to advance our Center goals to enhance the WNPRC marmoset colony as a national resource-commensurate with demand of investigators-and, develop WNPRC resource initiatives, such as a transgenic marmoset facility.